Energy-exergy analysis of ultra-supercritical biomass-fuelled steam power plants for industrial CHP, district heating and cooling

The use of biomass in combined heat and power (CHP) plants with district heating and cooling is necessary for achieving decarbonization targets. While in traditional biomass plants steam temperature is below 520 degrees C, new developments can lead to ultra-supercritical (USC) designs with steam temperatures of 600 degrees C. The present study investigates the performance of such plants for covering the heat demands of the aluminum and pulp and paper industrial processes, while also producing district heating and cooling. Plant performance is assessed through sensitivity analyses covering a wide range of heat demand scenarios. In the electricity-only scenarios, the electric and exergetic electric efficiencies of the aluminum/pulp and paper plants are 43.45/44.22% and 38.93/39.62%, respectively. In the CHP scenario, when the heat demand is maximized, the electric, exergetic electric, CHP and exergetic CHP efficiencies of the aluminum/pulp and paper plants are 21.81%/34.32%, 19.54%/31.70%, 92.50%/86.76% and 39.43%/39.01%, respectively. With the integration of cooling, the electric and CCHP efficiencies of the aluminum plant are 21.60% and 89.23%, respectively. Most of the exergy is destroyed during the combustion and steam generation processes, corresponding to 67-70% and 13-16% of the total exergy destruction, respectively. (C) 2020 The Authors. Published by Elsevier Ltd.